Evolution of the Bedrock of Finland: An Overview

Abstract

The Precambrian bedrock of Finland forms the core of the Fennoscandian Shield. The Archean area includes exposed Archean rocks (23%) and Archean crust overlain by Paleoproterozoic supracrustal and plutonic rocks (30%). The Proterozoic area is composed of the Paleoproterozoic Svecofennian Province (41%) intruded by rapakivi granites (4%).

The Archaean crust in Finland includes some older (>2.9 Ga) domains within the dominantly 2.8–2.7 Ga granitoid-migmatite complexes. Volcano-sedimentary belts formed in within-plate (2.9–2.8 Ga) and in island arc (c. 2.75 Ga) environments. The Archean crust accreted at 2.75–2.70/2.65 Ga, exhumed at 2.65–2.63 Ga and then stabilized at c. 2.6 Ga. Terrestrial to shallow marine deposition of sedimentary rocks and incipient rifting and mafic magmatism, at 2.44, 2.22, 2.14–2.10 and 2.06 Ga, characterises the age period from 2.44 to 2.06 Ga.

The Svecofennian province in Finland includes hidden c. 2.0 Ga microcontinents, turbiditic sedimentary rocks, 1.92–1.88 Ga arc-type volcanic rocks and 1.90–1.80 Ga plutonic rocks. The formation of the Lapland-Kola orogen (1.94–1.86 Ga) and the composite Svecofennian orogen (1.92–1.79 Ga) are the main Paleoproterozoic orogenic events, where the latter is responsible for the main Paleoproterozoic crustal growth of the Fennoscandian Shield. Bimodal rapakivi granite association (1.67–1.54 Ga) is the last major input to the bedrock of Finland.

Heilimo E, Halla J, Huhma H (2011) Single-grain zircon U–Pb age constraints of the western and eastern sanukitoid zones in the Finnish part of the Karelian province. Lithos 121:87–99CrossRefGoogle Scholar